Texture painting. Why not mark all seams and unwrap later?
If you want a more simple approach to getting started with Texture Paint, then consider using 'Smart Unwrap' from the Unwrap menu - no need to mark any seams with this option, and you can get on to painting. If you decide you really need a better map, then you can create a second UV map with the correctly marked seams and then bring in the paint from the previous mapping to a new image with the Clone Tool using the second correct mapping.